Improvement in steaivl sljde-valves



fN. P. lSTEVENS.

l Improvement in Slide Valves. No.12ll-,297t Patentedmarhsnz.

l gaa/9 fr Qrricn.

IMPROVEMENT iN STEAM SLlDEVALl/ES.

Y Specification forming part of Letters Iatcnt No. 124,297, dated March 5, 1872.

To all persoas to whom these presents may come:

Beit known that I, NA'rnAN P. S'rEvnNs, of Hopkinton, of the county of Merrimack and State of NewHampshire, have made a new and useful invention having reference to Steam- En gine Valves 5 and do hereby declare the same to be fully described in the following specificationandrepresentedin the accompanyingdrawing, of Which- Figure 1 is a longitudinal section, and Fig. 2 a transverse section of a valve apparatus provided with my invention. Fig. 3 is an underside view of the valve. Fig. 4 is a top view, Fig. 5 an edge elevation, and Fig. 6 an under side view of the packing-rin g protector, to be hereinafter described.

The invention has special reference to the valve mechanism explained and represented in Letters Patent No. 116,370, dated June 27, 1871, and granted to me, and is to protect the packing-ring thereof from wear and to accomplih other useful results, as hereinafterspecine The valvechest A is surmounted with a hollow dome, G, and is made open at one or both of its opposite ends in manner so that the valve B may be introduced in to and drawn out of the chest through the open end thereof, the said valve being flat on its upper and lower faces, and the two being parallel, as shown. The dome C receives the steam through an induct, D, leading into it, and is encircled at its base by a groove, a, to contain a packing, b, which may be a metallic ring.

1n my patented valve apparatus this ring rested directly on the upper` surface of the valve, and, as a consequence, was subject to be worn thereby during the reciprocating rectilinear movements of the valve. As such ring presents a very small area of bottom surface, it is liable, when in direct contact with the valve,

to soon become worn thinner, and, as a consequence, to leak steam or be productive of other disadvant ageous results. I have combined with such ring, the valve and valve-case, a rin g-supporter and protector, which rests directly' on the valve and presents thereto a very much larger area of wearing surface. The ring rests di rectly on the said supporter or protector and encompasses the neck thereof.

T 1e valve is provided with two ports, o c, and a centra-l exhaustsch amber, d, arranged between the parts, which also are extended over the said chamber and to a common opening, e, at the top and middle of the valve, all bein g as shown in Fig. 1. The valve-seat has an exhaust-passage, j', arranged between the ports g gthatlead to the ends of the cylinder. Furthermore, there is in the bottom of the valve a rectangular groove, h, which encompasses the openings of such bottom, the same being as shown in Fig. 3, which is an under-side view of the valve, and also in Figs. 1 and 2. Where this groove h rests over the valveseat there is an auxiliary passage, t', which is extended down from the seat into the main exhaust-passa ge f, all being as represented.

/Vi th the valve and chest so made the steam is in both of the oblique ports c c at once, and while the valve is in movement the steam will be alternately delivered into the ports g g of the seat and exhausted into the chamber d, and thence into the main exhaust-passage f, the steam which may leak from the valve on its lower surface being received into or interrupted by the groove It, and caused to escape through the auxiliary passage t' into the main exhaust-passage j'. v

In the drawing the aforesaid protector of the packingring b is shown at Gr, it consisting of a flat annulus provided with a cylindrical neck, 7s, arranged with the base portion Z in manner as shown, all being formed as represented. The base Z, on two opposite sides, is truncated or formed with parallel edges or areal chords, as shown at m m, the remaining parts of the periphery of the base being circular arcs. The ringsupporter G is disposed -within a circular rabbet, H, at the base or lower part of the packing-ring chamber c, the ring being arranged in such chamber in manner as shown.

The ring to rest on the supporter is shown in top v iew in Fig. 7; in bottom view in Fig. 8; in edgeelevation in Fig. 9 5 and in trans verse section in Fig. 10. Y

In these figures the ring is represented as split or separated at n; as grooved around its periphery, as seen at o; and as having a circular groove in its bottom, as exhibited at p. The two grooves 0 p are connected by passages q q, leading from one into the other, as shown in Fig. 10. Furthermore, there is a groove or channel, r, formed around on the bottoni of the rin g-protectorG in manner as shown,

there being holes s s leading from such groove or channel upward through the base part ofthe protector, and communicating with the groove ,in the bottom of the ring.

The valve B while moving works against the bottom surface of the ring-protector G, and therefore in no respect can wear the packingring. The purpose of forming the ring-supporter G with the arcal chords on m or without the areal portions incident thereto is to allow air to pass from the steam-chest by the ringsupporter and into its interior passage, in order to prevent a vacuum being formed in the cylinder of the engine by the piston ,while at work after the steam may have been shut o.

To enable air to thus pass from the valvecase up by theedges of the ring-supporter, the valve Bis chamfercd or beveled at top on both sides and lengthwise of it, as shown at a a in Fi g. 2, and also in Fig. 13, which is a top view ofthe valve B.

The purpose of the two grooves in the ring, connected by passages, as set forth, is to intercept any steam that may leak at the bearing surfaces of the ring, and allow such to pass off down through the ring-supporter, and thence into the channel in its bottom, from whence it will escape through a passage, t, leading down through the valve into the groove h, hereinbefore mentioned. Within the valve B, or Within the pa-rtitions or parts between the ports c c and the exhaust-chamber d of such valve, are two cylindrical chambers, u u, provided with passages o t leading down through their bottoms, and also having passages leading out of their tops, as shown at w w, into the ports or passages c c. Within each of the said chambers a u is a valve, x, formed, as shown, in top viewin Fig. 11 and in' side view in Fig. 12. 1t has grooves y y arranged vertically in its periphery, and it also has a projection, z, on its top, all being as shown.

The purpose of these valve-chambers u u, valves as x, passages v and fw, arranged as represented, may be thus explained. After the exhaust-port becomes closed by the valve, the

piston, before completion of its stroke, has a short distance to travel in the cylinder, and as a consequence, will compress any steam or air which may be between such piston and the next adjacent head of the cylinder. Now, were it not for the chambers u, the valves w, and passages o and w, the air or steam so compressed would, by being forced against the valve B, have a tendency to press it upward off its seat, thereby causing the valve to leak, provided the pressure on its top should be less than that tending to elevate it. But, with the adjuncts described, the steam or air, instead of forcing the valve B upward, will pass up one of the passages fu into its valve-chamber u, and will force the valve :v thereof upward off its scat and escape through the passages y y of such valves, and thence through the exit-passages w w of the valve-chamber into the steampassage c. Thus the valve B will be saved from being forced off its seat under circumstances as specified.

I claim as my invention the following, viz:

l. I claim the packing-ring supporter and protector G, as arranged with the ring, the valve B and in a chamber in the valve-case, and with the induction-passage D thereof, all substantially as set forth and represented, whereby the valve, While in movement, moves independently of the ring-supporter, and the steam passes from the passage D through such supporter.

2. Also,the said packing-ring and supporter, as provided with the channels o p q rs, arranged in manner and to operate with the valve and its case, substantially as explained.

3. I claim the small auxiliary valves x their chambers u u, inducts fu @,and educts w w, as arranged in the valve in manner as described and represented-viz., between and with respect to the passage c and chamber d as shown.

NATHAN l?. STEVENS. Witnesses:

R. H. EDDY,

S. N. PIPER. 

